The present invention concerns a process of making an antenna lens comprising a lens core and a coating layer surrounding it.
Antenna lenses made of dielectric material are described in U.S. Pat. No. 4,769,646. These antenna lenses can have planar or also structured surfaces for forming a beam. The so-called Fresnel structure is an example of a known surface structure of an antenna lens. So that the antenna lens has as compact a structure as possible, it must have a short focal length. This may be achieved by using dielectric material for the lens that has a very high dielectric constant (.epsilon.&gt;9). As described in the disclosure of a dielectric antenna lens in U.S. Pat. No. 5,154,973, ceramic material fulfills this requirement for a high dielectric constant. Suitable ceramic materials given in that reference include, for example, CaTiO.sub.3, SrTiO.sub.3, BaO--Nd.sub.2 O.sub.3 --TiO.sub.2, BaTiO.sub.3 and ZnO. According to U.S. Pat. No. 5,154,973 the lens core or lens body made from a ceramic material is surrounded with coating layer in order to reduce reflections in the antenna lens as much as possible. This coating layer is then at its most effective, when it is made from a material with a dielectric constant that corresponds approximately to the square root of the dielectric constant of the lens core made from the ceramic material. The coating layer with which the lens core is coated is made of plastic according to the state of the art.
According to past experiences in the art large process engineering expenses are required to make a ceramic lens with a diameter greater than 20 cm.